Use of a polyamide molding composition with high melt stiffness for coextrusion with a high-melting-point polymer

Abstract

Multilayer composites are obtained from a molding composition which contains the following components: a) 100 parts by weight of polyamide and b) from 0.005 to 10 parts by weight of a compound having at least two carbonate units by coextruding with a molding composition based on a high-melting-point polymer whose crystallite melting point T m is at least 255° C. and/or whose glass transition temperature T g is at least 180° C.

1. A process for producing a multilayer composite, comprising: preparing a first molding composition that is a mixture of: (a) 100 parts by weight of at least one polyamide and (b) from 0.005 to 10 parts by weight of a compound having at least two carbonate units based on 100 parts by weight of the polyamide; and coextruding the first molding composition and a second molding composition comprising a high-melting-point polymer having a crystallite melting point Tm of at least 275° C.; wherein the at least one polyamide and the at least one compound having at least two carbonate units are not melted together until the first molding composition and the second molding composition are coextruded and wherein the first molding composition comprises one or more polyamides selected from the group consisting of PA6, PA610, PA66/6, PA612, PA1010, PA1012, PA1212, PA613, PA614, PA1014, PA11, and PA12. 
     
     
       2. The process according to  claim 1 , wherein the glass transition temperature T g  of the high-melting-point polymer is at least 190° C. 
     
     
       3. The process according to  claim 1 , wherein the crystallite melting point T m , of the high-melting-point polymer is at least 275° C. and the glass transition temperature T g  of the high-melting-point polymer is at least 190° C. 
     
     
       4. The process according to  claim 1 , wherein the compound having at least two carbonate units is used in the form of a masterbatch. 
     
     
       5. The process according to  claim 1 , wherein the polyamide of the first molding composition is obtained by carrying out a polymerization in the presence of a diamine or polyamine regulator. 
     
     
       6. The process according to  claim 1 , wherein the polyamide of the first molding composition comprises a transparent polyamide containing polymerized units of at least one mixture selected from the group consisting of terephthalic acid and an isomer mixture including 2,2,4- and 2,4,4-trimethylhexamethylenediamine; isophthalic acid and 1,6-hexamethylenediamine; terephthalic acid, isophthalic acid and 1,6-hexamethylenediamine; isophthalic acid, 3,3′-dimethyl-4,4′-diaminodicyclohexylmethane, and laurolactam; isophthalic acid, 3,3′-dimethyl-4,4′-diamino-dicyclohexylmethane and caprolactam; 1,12-dodecanedioic acid, 3,3′-dimethyl-4,4′-diaminodicyclohexylmethane; isophthalic acid, 4,4′-diaminodicyclohexylmethane and laurolactam; isophthalic acid, 4,4′-diaminodicyclohexylmethane and caprolactam; 1,12-dodecanedioic acid and 4,4′-diaminodicyclohexylmethane; and terephthalic acid, isophthalic acid, 3,3′-dimethyl-4,4′-diaminodicyclohexylmethane and laurolactam. 
     
     
       7. The process according to  claim 1 , wherein the first molding composition comprises from 0.01 to 5.0% by weight of the compound having at least two carbonate units. 
     
     
       8. The process according to  claim 1 , wherein the first molding composition comprises from 0.05 to 3% by weight of the compound having at least two carbonate units. 
     
     
       9. The process according to  claim 1 , wherein the compound having at least two carbonate units is an ester of a carbonic acid. 
     
     
       10. The process according to  claim 1 , wherein the compound having at least two carbonate units is at least one of a phenolic ester of a carbonic acid and an alcoholic ester of a carbonic acid. 
     
     
       11. The process according to  claim 1 , wherein the compound having at least two carbonate units is at least one of a polycarbonate based on bisphenol A and a block copolymer containing a block of polymerized bisphenol A units. 
     
     
       12. The process according to  claim 1 , wherein the compound having at least two carbonate units is in the form of a masterbatch comprising from 0.15 to 50% by weight of the compound having at least two carbonate units and a polyamide matrix material. 
     
     
       13. The process according to  claim 1 , wherein the high-melting-point polymer is at least one selected from the group consisting of a fluoropolymer, a polyamide, a copolyamide, a polyether ketone, a liquid-crystalline polymer, a polyphenylene sulfide, a polysulfone, a polyethersulfone, a polyetherimide, and a syndiotactic polystyrene. 
     
     
       14. The process according to  claim 1 , further comprising:
 at least one of storing and transporting the first molding composition before coextruding with the second molding composition.